After deregulation of the telecommunications market in many countries, new network operators are constantly appearing on the market, who for the time being are acting as carriers for long-distance connections and are attempting to take traffic away from the former monopoly and from their competitors with inexpensive long-distance rates. Usually, these carriers are dialed individually (call by call) for each call, by means of a so-called carrier access code, by consumers. A prerequisite for accepting long-distance traffic is switch-through contracts between the new network operators and the network operator with whom the subscribers are physically connected, in most cases the former monopoly.
However, the new network operators are also increasingly penetrating the local sector, and are attempting to bind consumers to them with fixed contracts and lucrative conditions. These customers (subscribers) are then permanently attached to the new network operator through “preselection” in the local switching centers with which they are physically connected. For these subscribers, the new network operator generally enters into switch-through contracts with the operators of the local switching centers but leaves the actual control of functions (features) to the operators of the local switching centers.
If the new network operator wants to get to the subscriber lines directly, it must make additional arrangements with the operator of the local switching center, in some manner, in that the network operator taps the subscriber lines directly at the main distribution frame and manages a separate local switching center.
This has the disadvantage, for a new network operator, that a separate switching center in the local network sector has to be provided for the network operator's customers, and this involves a high level of investment.